1. Field of the Invention
The present invention relates generally to a welding gun, and more particularly, to a welding gun supported by a robot.
2. Description of Related Art
Conventional welding guns are grouped into X-type (for example, disclosed in Japanese Patent Publication No. HEI 4-253576) and C-type.
In the X-type welding gun, as illustrated in FIG. 16, welding tips 4 and 5 are coupled to first ends 2A and 3A of two arms 2 and 3 which are pivotally coupled to each other at a connecting point 1, and a distance between second ends 2B and 3B of the two arms 2 and 3 is changed by an actuator 6 so that the welding gun is opened and closed. In the C-type welding gun, as illustrated in FIG. 17, welding tips 8 and 9 are coupled to opposite ends of a C-type frame, and a distance between the welding tips 8 and 9 is changed by an actuator 10 so that the welding gun is opened and closed.
However, because the welding tips of conventional welding guns move on a straight line, the arms and frame tend to interfere with a workpiece. This is illustrated in FIGS. 14 and 15 in which the interference is denoted by letter A. As a result, operation of the welding gun tends to be restricted. A maximum opening amount X.sub.1 of the welding tips and a protruding amount X.sub.4 of the welding tips from the body of the welding gun illustrated in FIGS. 16 and 17 tend to be restricted, so that the freedom in designing the welding gun is small.